Experimental investigation of the characteristics of flame geometry and heat transfer from wind-driven pool fires

Abstract

Wind-driven pool fire is a frequently encountered thermal hazard in cases of liquid fuel leakage accidents. Given the intricate interplay between wind flow and thermal buoyancy, understanding the flame geometry and external heat transfer behavior of pool fires is vital for effective liquid fuel security management. This paper presents a study to investigate these characteristics under various square pool sizes (side length, D = 0.31, 0.38, 0.44, 0.49, and 0.54 m) and wind speeds (u = 0, 0.5, 1, 2, 4, and 6 m/s). Five parameters pertaining to global flame geometry and two parameters concerning external heat transfer were measured. The findings indicate that the change rate of overall flame geometry parameters accelerates at first and then decelerates with wind speed. The ratio of the net flame horizontal length dominated by inertia force (Li) and the net flame horizontal length dominated by buoyancy force (Lb) to the total horizontal flame length (Lh) (Li / Lh and Lb / Lh) present a non-monotonic trend with increasing Fr number. To further comprehend the global flame geometry, a corresponding physical model is developed based on the ratio of Grs number to the 5/2 power of Rem number (Grs / Rem5/2). Due to the effects of flame thickness and flame attachment length, the variation in radiant heat transfer with wind speed can be bifurcated into two categories. The convective heat coefficient increases with wind speed, enhancing the local convection. Finally, the new models of radiant and convective heat transfers are established using dimensionless wind speed (u*, u∗=u(ṁ″g/ρ0)1/3) and Ri number. To ascertain the suitability of these new models, they have been validated against two classic flame models.